Mycoplasma genitalium

Mycoplasma genitalium
Scientific classification
Kingdom:	Bacteria
Division:	Firmicutes
Class:	Mollicutes
Order:	Mycoplasmatales
Family:	Mycoplasmataceae
Genus:	Mycoplasma
Species:	M. genitalium
Binomial name
Mycoplasma genitalium Tully et al., 1983

Mycoplasma genitalium is a small parasitic bacterium that lives on the ciliated epithelial cells of the primate genital and respiratory tracts. M. genitalium is the smallest known genome that can constitute a cell, and the second-smallest bacterium after the recently-discovered endosymbiont Carsonella ruddii. Until the discovery of Nanoarchaeum in 2002, M. genitalium was also considered to be the organism with the smallest genome.^[1] There is a difference between smallest parasitic bacteria and smallest free living bacteria. The smallest known free living bacteria is the thermophile Aquifex aeolicus with 1.5 Mb and 1512 genes.^[2]

Overview

Mycoplasma genitalium was originally isolated in 1980 from urethral specimens of two male patients with non-gonococcal urethritis. Infection by M. genitalium seems fairly common, can be transmitted between partners during unprotected sexual intercourse, and can be treated with antibiotics; however, the organism's role in genital diseases is still unclear.

The genome of M. genitalium consists of 521 genes (482 protein encoding genes) in one circular chromosome of 582,970 base pairs. An initial study of the M. genitalium genome with random sequencing was performed by Peterson in 1993. It was then sequenced by Fraser and others. It was found to contain only 470 predicted coding regions, including genes required for DNA replication, transcription and translation, DNA repair, cellular transport, and energy metabolism.^[3] It was the second complete bacterial genome ever sequenced, after Haemophilus influenzae. The small genome of M. genitalium made it the organism of choice in The Minimal Genome Project, a study to find the smallest set of genetic material necessary to sustain life.

Symptoms

Various symptoms of infection: An infected person may have some or all symptoms, or may be asymptomatic.

• Urethritis (in men)
• Discharge (both sexes)
• Burning while urinating (both sexes)
• Arthritis/reactive arthritis (mostly men)
• Vaginal itching (women)
• Pain during intercourse (women)

This infection is associated with bacterial vaginosis. In the long term, this infection is suspected to cause pelvic inflammatory disease.

Treatment

The CDC recommends using^[4] one of these treatments, in this order of prevalence (the first is known to be the most effective, the others are alternative treatments)

• Azithromycin 1 g orally in a single dose
• Doxycycline 100 mg orally twice a day for 7 days
• Erythromycin base 500 mg orally four times a day for 7 days
• Erythromycin ethylsuccinate 800 mg orally four times a day for 7 days
• Ofloxacin 300 mg orally twice a day for 7 days
• Levofloxacin 500 mg orally once daily for 7 days

However, this study Azithromycin Failure in Mycoplasma genitalium Urethritis says that "...doxycycline and levofloxacin have substantial failure rates..." and "...Recurrent urethral symptoms following azithromycin therapy only occurred in persons with persistent M. genitalium infection and resolved with moxifloxacin."

So moxifloxacin appears to be an alternative treatment after one of the other treatments have already failed (Azithromycin 1g is the preferred first-line treatment).

Synthetic life

In October 2007, a team of scientists headed by DNA researcher Craig Venter and Nobel laureate Hamilton Smith announced that they plan to create the first artificial life form in history by creating a synthetic chromosome, which they plan to inject into the M. genitalium bacterium, with potential to result in an artificial species dubbed Mycoplasma laboratorium or Mycoplasma JCVI-1.0 after the research centre in which it was created, the J. Craig Venter Institute in the United States.^[5][6]

On 24 January 2008, the same team reported to have synthesized the complete 582,970-base pair genome of M. genitalium (a key gene that enables the wild organism to cause disease was knocked out). The final stage of synthesis was completed inside a M capricolum, which had its DNA removed, with the help of yeast cells.^[7] On 20 May 2010 they reported success with a similar process, using instead the genome of Mycoplasma mycoides, creating what some called the first artificial life.^[8]

See also

• The Minimal Genome Project
• Candidatus Carsonella ruddii
• Arthritis / Reactive arthritis / Septic arthritis

References

1. ^ Aside from viruses—however, it is not agreed upon as to whether or not viruses constitute life.
2. ^ Genes IX, Benjamin Lewin, page 78.
3. ^ Fraser, Claire M.; et al. (1995). "The Minimal Gene Complement of Mycoplasma genitalium". Science 270 (5235): 397–404. doi:10.1126/science.270.5235.397. PMID 7569993. 
4. ^ http://www.cdc.gov/std/treatment/2006/urethritis-and-cervicitis.htm#uc2
5. ^ Pilkington, Ed (2007-10-06). "I am creating artificial life, declares US gene pioneer". The Guardian. http://www.guardian.co.uk/science/2007/oct/06/genetics.climatechange. 
6. ^ Briggs, Helen (2008-01-24). "Synthetic life 'advance' reported". BBC News. http://news.bbc.co.uk/1/hi/sci/tech/7203186.stm. 
7. ^ Ball, Philip (2008-01-24). "Genome stitched together by hand". Nature News. doi:10.1038/news.2008.522. http://www.nature.com/news/2008/080124/full/news.2008.522.html. 
8. ^ Swaby, Rachel. [On 20 May 2010 they report success with the implantation of th "Scientists Create First Self-Replicating Synthetic Life"]. Wired. On 20 May 2010 they report success with the implantation of th. Retrieved 21 May 2010. 

External links

• Mycoplasma genitalium Reference Work at the UK Health Protection Agency
• Mycoplasma genitalium G-37 genome page